1. Field of the Disclosure
The instant disclosure relates to a circuit for pin assignment detection; in particular, to a circuit for microphone pin assignment detection and method thereof.
2. Description of Related Art
Microphones come in all sorts of shape and size including moving-coil microphone, capacitor microphone, electret capacitor microphone, microelectromechanical microphone and aluminium ribbon microphone. The electret capacitive and the microelectromechanical account to capacitor microphones, while the manufacturing process and internal circuitry are different. Conventional consumer electronic products, for example, mobile phones, personal digital assistance and the like, adapt capacitor microphones.
A headset with 3.5 mm and 4 pins may employ two types of specification respectively. These two types include Open Mobile Terminal Platform (OMTP) and Cellular Telecommunications & Internet Association (CTIA). The difference between the OMTP and the CTIA arises from the pin assignment where the signal terminal and the ground terminal of the microphone connector may be reversed. Under inappropriate connection, it may result in failure of the microphone functions. Typically, it is overcome by a converter or a jumper.
Fairchild suggests a detection chip which detects and switches the pins. However, the detection chip requires an initializing signal from an external processor and includes an oscillator and a timer, which adds the complexity to the design.